{"id":59749,"date":"2024-06-04T08:38:11","date_gmt":"2024-06-04T08:38:11","guid":{"rendered":"http:\/\/e911d2e3-e3b2-4148-8c5c-78b041bb26bd"},"modified":"2024-06-04T08:39:47","modified_gmt":"2024-06-04T08:39:47","slug":"cosmic-explosions-expanding-universe-and-the-threat-to-earth-astronomer-answers-5-questions-hes-most-often-asked","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/cosmic-explosions-expanding-universe-and-the-threat-to-earth-astronomer-answers-5-questions-hes-most-often-asked\/","title":{"rendered":"Cosmic explosions, expanding Universe and the threat to Earth. Astronomer answers 5 questions he&#8217;s most often asked"},"content":{"rendered":"<p class=\"rssexcerpt\">Nial Tanvir is a Professor in Physics and Astronomy at the University of Leicester, UK. We asked him to answer 5 of his most-asked questions. <\/p><p class=\"rssauthor\">By Nial Tanvir\n      <\/p><p class=\"rssbyline\">Published: Tuesday, 04 June 2024 at 08:38 AM<\/p><hr class=\"no-tts wp-block-separator\"\/><?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n<!DOCTYPE html PUBLIC \"-\/\/W3C\/\/DTD HTML 4.0 Transitional\/\/EN\" \"http:\/\/www.w3.org\/TR\/REC-html40\/loose.dtd\">\n<html><body><p>\u2009My research mainly focuses on transient phenomena that come and go, particularly extremely powerful explosions known as <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/what-is-a-gamma-ray-burst\">gamma-ray bursts<\/a> (GRBs).<\/p><p>Some of these are produced by the deaths of massive stars, while others are from the mergers of binary <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/neutron-star\">neutron stars<\/a>.<\/p><figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\"><iframe loading=\"lazy\" title=\"Piecing together the history of the Universe\" width=\"800\" height=\"450\" src=\"https:\/\/www.youtube.com\/embed\/vMvl7FsJrfc?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen=\"\"\/><\/div><figcaption class=\"wp-element-caption\">Video interview with Nial Tanvir at the International Astronomy Show<\/figcaption><\/figure><p>As my work deals with cosmic explosions, the early Universe, black holes and the Big Bang, I&#8217;m often asked a lot of questions by people who want to know more about these incredible phenomena.<\/p><p>The five questions I\u2019m always asked about my research are:<\/p><h2 class=\"wp-block-heading\" id=\"h-where-did-the-big-bang-occur\"><strong>Where did the Big Bang occur?<\/strong><\/h2><p>The surprising thing we find, looking far across the Universe, is we essentially see a similar distribution<br\/>of galaxies in every direction.<\/p><p>There\u2019s no special place that could represent the centre of the Universe.<\/p><p>In fact, this is built into the foundations of the Big Bang theory, which starts by assuming a symmetrical Universe.<\/p><p>It also assumes it is infinite, meaning there is no centre and every point has essentially the same experience.<\/p><p>The Big Bang isn\u2019t an explosion in space, but more an explosion of space.<\/p><figure class=\"wp-block-image size-full\"><figcaption class=\"wp-element-caption\">Illustration showing the expansion of the Universe from the Big Bang to the present day.Credit: Andreus \/ iStock \/ Getty Images Plus<\/figcaption><\/figure><h2 class=\"wp-block-heading\" id=\"h-do-galaxies-move-faster-than-the-speed-of-light\"><strong>Do galaxies move faster than the speed of light?<\/strong><\/h2><p>It depends on how one defines distance and time.<\/p><p>It is true that under certain ways of looking at distance, faraway <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/do-galaxies-move\">galaxies are receding from us<\/a> faster than the <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/speed-of-light\">speed of light<\/a>, breaking the cosmic speed limit.<\/p><p>But if we regard that as the space between us and the distant galaxy <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/does-universe-expand-faster-than-light\">expanding faster than the speed of light<\/a>, then nothing is moving faster than the speed limit relative to other matter in its vicinity.\u00a0<\/p><h2 class=\"wp-block-heading\" id=\"h-how-do-we-see-gamma-ray-bursts-from-13-billion-years-ago-wouldn-t-their-light-have-passed-us-by-now\"><strong>How do we see gamma-ray bursts from 13 billion years ago? Wouldn\u2019t their light have passed us by now?<\/strong><\/h2><p>It\u2019s a very good question and one of those aspects of the <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/before-big-bang\">Big Bang<\/a> theory that challenges our intuition.<\/p><p>We already said the space between us and distant galaxies is expanding, so the light from them is continually playing catch-up in its journey from there to here.<\/p><p>This means that some of the light is only just reaching us, and we see distant objects as they were in early times in the Universe.<\/p><figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2023\/11\/Gamma-ray-burst-221009A-1024x683.jpg?fit=800%2C534\" alt=\"Gamma-ray burst 221009A hit Earth's atmosphere. Image captured by the XMM-Newton mission. Credit: ESA\/XMM-Newton\/M. Rigoselli (INAF)\" class=\"wp-image-143067\" data-recalc-dims=\"1\"\/><figcaption class=\"wp-element-caption\">Gamma-ray burst 221009A hit Earth&#8217;s atmosphere. Image captured by the XMM-Newton mission. Credit: ESA\/XMM-Newton\/M. Rigoselli (INAF)<\/figcaption><\/figure><h2 class=\"wp-block-heading\" id=\"h-if-the-creation-of-black-holes-creates-grbs-shouldn-t-everything-fall-in-the-black-hole\"><strong>If the creation of black holes creates GRBs, shouldn\u2019t everything fall in the black hole?<\/strong><\/h2><p>When a large enough star collapses, it is initially just the central core that forms the <a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/black-hole\">black hole<\/a>.<\/p><p>The hole is only a few miles across (compared to millions of miles for the star).<\/p><p><a href=\"https:\/\/www.skyatnightmagazine.com\/space-science\/what-is-gravity-facts-about-force\">Gravity<\/a> will cause material to fall into it, but the star\u2019s rotation will initially cause it to miss and be drawn into a disc around it.<\/p><p>In the process, the potential energy of the matter gets transformed into heat, rotational velocity, magnetic energy and so on.<\/p><p>The surprising thing is that a fair fraction of this energy goes into powering very fast-moving jets or beams of outflowing plasma, and it is these that create gamma-ray bursts.<\/p><p>Exactly how this occurs is still being researched, but it\u2019s probably the result of the star\u2019s magnetic field being wound up like a rubber band, throwing out matter when it unwinds.<\/p><figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" src=\"https:\/\/c02.purpledshub.com\/uploads\/sites\/48\/2020\/08\/gamma-ray-bursts-cf98478.jpg\" alt=\"A Hubble Space Telescope image showing a number of galaxies thought to host bright gamma-ray bursts. Credit: NASA, ESA, A. Fruchter (STScI), and the GOSH Collaboration\" class=\"wp-image-52026\"\/><figcaption class=\"wp-element-caption\">A Hubble Space Telescope image showing a number of galaxies thought to host bright gamma-ray bursts. Credit: NASA, ESA, A. Fruchter (STScI), and the GOSH Collaboration<\/figcaption><\/figure><h2 class=\"wp-block-heading\" id=\"h-could-grbs-be-a-threat-to-earth-nbsp\"><strong>Could GRBs be a threat to Earth?\u00a0<\/strong><\/h2><p>GRBs are so powerful they could pose a threat to life on Earth if one occurred in the Milky Way.<\/p><p>Fortunately they are very rare, even rarer in galaxies like ours.<\/p><p>In practice they\u2019re not a great risk, but it\u2019s still important that we improve our understanding of them, to identify potentially threatening systems nearby.<\/p><p><strong><em>Do you have any questions about the Universe? Email us at <a href=\"mailto:contactus@skyatnightmagazine.com\" target=\"_blank\" rel=\"noreferrer noopener\">contactus@skyatnightmagazine.com<\/a> and they could be answered in a future issue.<\/em><\/strong><\/p><p><strong><em>This article appeared in the November 2022 issue of BBC Sky at Night Magazine<\/em><\/strong><\/p> <\/body><\/html>\n<hr class=\"no-tts wp-block-separator\"\/>","protected":false},"excerpt":{"rendered":"<p>Nial Tanvir is a Professor in Physics and Astronomy at the University of Leicester, UK. 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We asked him to answer 5 of his most-asked questions.","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed\/59749"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/59750"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=59749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=59749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}